Escalator dual solenoid main drive shaft brake

Abstract

A main drive shaft brake for a passenger conveyor includes a braking element, an actuator, and a counter-actuator. The actuator is de-energized to release the braking element and halt operation of the passenger conveyor during an abnormal or emergency condition. An energized counter-actuator permits release of the braking element but, when de-energized, inhibits release of the braking element by the actuator to prevent unintentional release of the braking element caused by, for example, an accidental loss of power to the actuator.

The invention claimed is: 
     
       1. A main drive shaft brake for a passenger conveyor, the brake comprising:
 a braking element for halting movement of a driving mechanism in the passenger conveyor system; 
 an actuator connected to the braking element for controlling activation of the braking element, the actuator movable between an energized mode, in which power supplied to the actuator keeps the braking element in a ready position, and an un-energized mode, in which a lack of power supplied to the actuator causes the actuator to release the braking element, thereby halting movement of the driving mechanism in the passenger conveyor system; and 
 a counter-actuator connected to the actuator, the counter-actuator movable between an energized mode in which power supplied to the counter-actuator keeps the counter-actuator from interfering with the actuator, and an un-energized mode, in which a lack of power causes the counter-actuator to block the release of the braking element. 
 
     
     
       2. The brake of  claim 1 , wherein the passenger conveyor system is an escalator or a moving walkway. 
     
     
       3. The brake of  claim 1 , wherein the actuator and counter-actuator comprise a first solenoid and a second solenoid, respectively. 
     
     
       4. The brake of  claim 3 , wherein the actuator and the counter-actuator further comprise a first coil and a second coil, respectively. 
     
     
       5. The brake of  claim 4 , wherein the counter-actuator comprises a non-magnetic buffer that blocks the release of the braking element by the actuator. 
     
     
       6. The brake of  claim 1 , wherein the brake is resettable after the braking element is released. 
     
     
       7. A main drive shaft brake for a passenger conveyor, the brake comprising:
 a braking element; 
 a release lever connected to the braking element for holding the braking element in a lifted and ready position or releasing the braking element to halt movement of the conveyor, 
 an actuator having a first coil adjacent to the release lever and a first stroke extending into the first coil, the first stroke capable of moving further into the first coil to enable the release lever to release the braking element; and 
 a counter-actuator opposite to the actuator, the counter-actuator having a second coil and a second stroke extending into the second coil, the second stroke being biased by a spring such that a loss of power causes the second stroke to block the first stroke from moving further into the first coil, thereby preventing release of the braking element. 
 
     
     
       8. The brake of  claim 7 , wherein second stroke includes a buffer end opposite the spring such that a loss of power causes the buffer end of the second stroke to block the first stroke. 
     
     
       9. The brake of  claim 8 , wherein the buffer end comprises a non-magnetic material. 
     
     
       10. The brake of  claim 7 , wherein power supplied to the first coil causes the first stroke to move away from the second coil. 
     
     
       11. The brake of  claim 10 , wherein power supplied to the second coil causes the second stroke to move away from the first coil. 
     
     
       12. The brake of  claim 7 , wherein a space between the first coil and the second coil is dimensioned such that only one of the first stroke and the second stroke can occupy the space at any given time. 
     
     
       13. The brake of  claim 7 , wherein the release lever comprises a base and an arm extending from one side of the base, the base being connected to a release spring and the braking element, the arm being connected to the actuator. 
     
     
       14. The brake of  claim 7 , wherein the braking element is a wedge brake. 
     
     
       15. The brake of  claim 7 , wherein the actuator comprises a release solenoid and the counter-actuator comprises a line solenoid. 
     
     
       16. The brake of  claim 7 , wherein the passenger conveyor is an escalator or a moving walkway. 
     
     
       17. A method of controlling a main drive shaft brake for a passenger conveyor, the method comprising:
 controlling an electrically controlled brake actuator in either an energized state, such that the brake actuator holds the main drive shaft brake in lifted position, or a de-energized state to cause the brake actuator to release the main drive shaft brake to a dropped position; and 
 inhibiting the brake actuator from releasing the main drive shaft brake in response to a loss of line power. 
 
     
     
       18. The method of  claim 17 , wherein the step of inhibiting the brake actuator comprises:
 maintaining a counter-actuator in an energized state such that it is only de-energized in response to a loss of line power. 
 
     
     
       19. The method of  claim 18 , wherein a loss of line power causes the brake actuator and the counter-actuator to de-energize approximately simultaneously, and wherein the counter-actuator inhibits the brake actuator from releasing the main drive shaft brake. 
     
     
       20. The method of  claim 19 , further comprising:
 resetting the main drive shaft brake and brake actuator by re-energizing the actuator. 
 
     
     
       21. A passenger conveyor comprising:
 a driving mechanism; 
 a drive sheave in contact with the driving mechanism for imparting motion thereto; and 
 a main drive shaft brake associated with the drive sheave, the main drive shaft brake including a braking element for halting rotation of the drive sheave, an actuator for controlling activation of the braking element, and a counter-actuator for blocking an unintentional activation of the braking element. 
 
     
     
       22. The passenger conveyor of  claim 21 , wherein the actuator is movable between an energized mode, in which power supplied to the actuator keeps the braking element in a ready position, and an un-energized mode, in which a lack of power supplied to the actuator causes the actuator to release the braking element, thereby halting movement of the driving mechanism in the passenger conveyor system. 
     
     
       23. The passenger conveyor of  claim 22 , wherein the counter-actuator is movable between an energized mode in which power supplied to the counter-actuator keeps the counteractuator from interfering with the actuator, and an un-energized mode, in which a lack of power causes the counter-actuator to block the release of the braking element. 
     
     
       24. The passenger conveyor of  claim 21  wherein the counter-actuator inhibits activation of the braking element in response to a loss of line power.